Catheters are commonly used to provide quick and direct access to a patient's blood stream. Commonly used catheters range from intravenous lines, which are used in a variety of routine situations, to central venous catheters (CVC), which are used in critical care situations. Catheter maintenance can be costly and troublesome, especially for all but the simplest short-term catheters such as those which access a patient's arm vein.
For example, a CVC is inserted by a surgical procedure in a vein very near the heart. A CVC is often left in place for a relatively long time. The skin entry point is kept covered by a carefully monitored dressing. Because of the direct nature of access to the blood stream, infection control when dealing With CVCs is of utmost importance. In most institutions, only registered nurses and doctors are allowed to perform procedures relating to CVC access.
A CVC includes one or more external access lumens, each having a terminus injection/withdrawal port which typically includes a needle-less connector such as a Luer-lok connector. To allow injection or withdrawal of fluids through the CVC, the connector is typically connected to a mating piece having a pierceable rubber membrane. Fluid transfer requires first cleaning the pierceable membrane with alcohol and/or Betadine, and then inserting a hypodermic syringe needle through the membrane to provide direct access to the blood stream. In some cases, syringes are connected directly to the CVC's connector without a needle, thereby eliminating the need for the pierceable membrane.
CVC access lumens can become clogged by clotted blood and fibrin. The access lumens are kept free from clots when not in use by injecting a heparin solution into them. This is commonly referred to as a heparin lock. Heparin is a protein material which acts as a blood anticoagulant. Before withdrawing a blood sample from a CVC, the heparin and the blood-containing heparin in the catheter is first withdrawn. Also, depending on the patient's condition and the type of catheter, it is sometimes desirable or necessary to withdraw heparin from the catheter before injecting a medication through the catheter.
There are significant risks associated with transferring fluid through a CVC. One risk is that of microbial infection. Another significant risk is that of air embolism. Both of these risks are potentially life-threatening and increase significantly with each access through the CVC access lumen, especially when such an access is by way of a needle and pierceable membrane. Compounding these risks is the fact that a single medication injection procedure or a single blood collection procedure can require four or more separate connections to the CVC access lumen, one for each separate fluid injection and withdrawal. In some cases, the CVC is used for medication injection or blood withdrawal as many as four to six times each day. Thus, as many as twenty-four CVC connections are required every day, with a corresponding number of opportunities for infection or air embolism. Over the period of a month, the CVC could present over 700 opportunities for life-threatening events to occur.
As an example, a simple medication injection procedure requiring heparin withdrawal includes the following steps. First, the pierceable membrane of the injection port must be cleaned with alcohol. The success of this step is highly dependent on the skill of the care-giver and is subject to mistakes caused by carelessness or inattentiveness. A needle of a waste blood withdrawal syringe is then inserted through the membrane. The syringe is operated to withdraw the heparin-containing blood from the CVC. Next, the catheter is flushed with a saline syringe. A medication syringe is then prepared, its needle inserted through the pierceable membrane, and medication injected into the CVC. Subsequently, another saline flush syringe is prepared and its contents injected to carry all the medication into the patient's blood stream. Finally, heparin is injected into the CVC through the pierceable membrane to re-establish the heparin lock. If all this is done quickly and correctly, the catheter will not clot, no air embolism will result, and the patient will not be infected.
Withdrawing or collecting blood requires similar steps. First, all heparin-containing blood is withdrawn from the CVC transfer lumen by injecting a needle through the pierceable membrane and withdrawing blood into a waste blood withdrawal syringe. After the heparin-containing blood is completely withdrawn from the catheter, the waste withdrawal needle is removed and a needle of another syringe is inserted to withdraw non-heparin contaminated blood. Then a normal saline flush is injected, followed by a heparin injection with yet another needle and syringe to establish a heparin lock.
As is apparent from the above discussion, another problem with standard CVC access procedures is that the various solutions and syringes needed to access a CVC are supplied separately. A nurse must often collect these materials from different places. This can be a costly and time consuming process. Furthermore, even after proper equipment is found it is often not designed to work together as a system.
In part because of this, CVC procedures are performed only by registered nurses or doctors, with the procedure consuming a large quantity of their valuable time. The patient and other care-givers are often forced to remain idle while waiting for the qualified persons to find time to provide the catheter access service.
As an additional complication, access to a CVC by needle gives rise to a potential source of injury and infection to the care-giver through contact with the needle. This is particularly important when the patient being treated has a dangerous infection, such as HIV or hepatitis. Often, the care-giver and patient are unaware that an infection is present.
In addition to CVC maintenance and operation as described above, it can be highly desirable in emergency situations to get a plurality of medications quickly into a patient's bloodstream through a CVC or other catheter. It would be highly desirable in such situations for the care-giver to have a catheter access system which facilitates multiple accesses to the catheter.
Our U.S. Patent No. 5,308,322, formerly U.S. patent application Ser. No. 08/048,906, and our U.S. Pat. No. 5,411,485, formerly U.S. patent application Ser. No. 08/187,632, are hereby incorporated by reference.